Magnetic coil convergence assembly



Feb. 28, 1967 N. KRIADIS MAGNETIC COIL CONVERGENCE ASSEMBLY .5104 MW MA sx A f 6 9 l a 524 u f Q 6 N D a; d MR m Z M ,EZECTRON iERARI 51 & 2

Unitcd States Patent 3,307,128 MAGNETIQ COIL CONVERGENCE ASSEMBLY Nickolas Kriadis, Itasca, Ill., assignor t0 Bel-Tronics Corporation, Addison, 11]., a corporation of Illinois Filed Dec. 11, 1964, Ser. No. 417,607 8 Claims. (Cl. 335-212) This invention relates to magnetic coil assemblies, and more particularly to an improved magnetic assembly for use in the electron beam convergence control means of color television picture tubes.

Presently one general type of color television picture tube in wide commercial usage employs three separate electron beams which are adjustabl-y controlled to converge on a so-c-alled aperture or shadow mask positioned adjacent to the face of the picture tube. In order to cause the beams to converge, magnetic coil convergence assemblies are mounted on the neck of the picture tube. These convergence assemblies include current receiving coils wound on ferrite cores to provide dynamic convergence of the three beams, and. permanent magnets to provide static convergence of the beams.

In forming one prior known type of said magnetic coil convergence assemblies, the coils are wound on hollow blanks which blanks are then inserted around the legs of a U-shaped ferrite core. Generally two separate coils formed of relatively fine wire are mounted on each leg of the core, i.e., there are a total of four coils mounted on a core. As can be readily appreciated, each coil includes two extending or terminal wires which need to be affixed to appropriate terminal posts. And, if four coils are used, a total of eight free or dangling wires must be connected. to appropriate terminal posts. Thus, the assembling operator has to separate the various dangling wires and route them and connect them to the appropriate terminals. This is time consuming, expensive and tends to produce errors in making the connections.

Accordingly, it is a principal object of the present invention to provide an improved magnetic coil assembly in which the mounting of the coils on the core is simplified.

It is another object of the present invention to provide a magnetic coil assembly in which the coils may be connected to terminal posts prior to mounting on the associated core.

It is another object of the present invention to provide a magnetic coil assembly in which the assembly is formed as two separate units which are thereafter joined together.

It is yet another object of the present invention to provide a magnetic coil assembly in which errors in the connections of the coils are minimized.

In one preferred embodiment, the invention provides a magnetic coil assembly, having two similar mating blanks or forms, said forms having spaced sections on which individual coils may be wound and having terminal connectors to which the ends of the coils may be connected to initiate and terminate the winding of the coils, and said forms further including guideway for mounting and adjustably positioning a permanent magnet holder.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings.

In the drawings:

FIGS. 1, 2, 3 and 4 are sketches useful in explaining background information concerning the invention;

FIG. 5 shows an exploded view of the two half units of the magnetic coil assembly blank or form in accordance with the invention;

FIG. 6 shows a side view of the magnetic coil assembly of FIG. 5 and indicating the mounting of a holder carrying a permanent magnet.

FIG. 7 shows a view of the over-all magnetic coil assembly before the coils are wound thereon.

FIG. 8 shows the completed magnetic coil assembly in accordance with the invention including the coils Wound thereon.-

As mentioned above, one type of picture tube presently in commercial use in color television sets, employs three separate electron beams emanating from three separate guns to activate three primary colors and hence is known as a three gun or three color tube. The three primary colors used are red, blue and green and are provided by three different kinds of phosphors deposited on the viewing screen or face of the tube, see FIG. 1. These phosphors are caused. to glow in the three primary colors when excited by the respective high velocity electron beams and these primary colors are added to one another to provide good color reproduction. The proportion or control means by which the three primary colors are added together take advantage of the characteristic of the human eye of having a persistence of vision effect, and also of the inability of the eye to separate very fine detail. Accordingly, the picture on the picture tube may be divided into many small color elements composed of groups of primary colors. When these elements are ex cited at a sufliciently rapid sequential rate, the persistence of vision of the eye will make it to appear as if the elements are excited simultaneously. This characteristic of the eye thus automatically provides color addition. Moreover, if the picture elements in the groups of primary colors are positioned to be sufficiently close, the eye cannot see them as separate color elements and blends them together into a single color.

In the three gun tubes, the viewing screen consists of very closely spaced groups of phosphor dots with three dots in each group as shown in FIG. 1. One dot in each group is red, one dot is green and the other dot is blue. In one commonly used picture tube, in a screen area of about 270 square inches there are about 300,000 groups of 900,000 phosphor dots arranged as shown in FIG. 1.

An aperture or shadow mask is arranged to be similar in shape to the face or viewing screen of thepicture tube. The shadow mask has an array of closely spaced holes equal in number to the groups of phosphor dots. Each hole is accurately aligned with respect to a group of dots, and each electron beam must be aimed through a shadow mask hole so that it will reach only phosphor dots of one particular color. Thus, the beam from the gun associated with the blue phosphors should excite only blue phosphor dots, the beam associated with the green phosphors excites only green phosphor dots and the beam associated with the red phosphors excites only red phosphor dots. The beams are electronically controlled to scan the entire shadow mask to thus advance sequentially from hole to hole in the shadow mask.

As indicated in FIG. 1 and in order for the picture tube to operate properly the three beams must be arranged and controllably adjusted to converge at the holes or apertures in the shadow mask and each of the beams must be guided to impinge on the proper colored dot by a suitable magnetic convergence assembly.

As shown in FIGS. 2 and 3, the three magnetic coil assemblies 9, 9A and 9B, when mounted on a picture tube comprise a magnetic convergence unit of three assemblies. Each convergence assembly 9, 9A and 9B controllably adjusts a respective one of the three electron beams. FIGS. 2 and 3 show the positioning and relative orientation of the magnetic assemblies of the invention posithe flange.

tioned on the neck of a color picture tube. In FIGS. 2 and 3 only the magnetic convergence assemblies 9, 9A and 9B are shown. The other components which are mounted on a television tube are not part of this invention and are omitted, for purposes of simplicity in the drawing and in the description.

Referring to FIG. 3, the magnetic convergence assembly 9 includes a permanent magnet 29 which is adjustably positioned as indicated to move the top or blue beam in a vertical direction as indicated by the arrows 51 to adjust the static convergence of the blue beam. That is, the permanent magnet 29 is adjusted so that the blue electron beam impinges at the desired position at the center of the picture tube. Likewise the permanent magnets 29A and 29B in assemblies 9A and 3B move the red and green beams in the direction indicated by the arrows 51A and 51B respectively. In addition to the vertical movement of the blue beam, a horizontal movement of the blue beam may be accomplished by the adjustment of a so-called blue lateral magnet, not shown, also located on the neck of the picture tube.

Refer now to FIG. 4. While the aperture or shadow mask is of spherical shape, its curvature does not coincide with an arc 40 formed when the electron beam of a given length is scanned over the surface of the shadow mask. Therefore, while static convergence may occur at the center of the shadow mask, it does not necessarily occur at points away from the center. To insure that convergence will occur at all points on the aperture mask, a dynamic convergence signal is derived from the horiontal and vertical deflection circuits of the television set and applied to the coils of each of the assemblies 9, 9A

and 9B. This causes the magnetic field in each of the magnetic convergence assemblies 9, 9A and 9B to vary in accordance with the instantaneous position of the beams at the aperture mask during the scanning cycle; and, accordingly, the convergence of the beams becomes a function'of the instantaneous deflection voltage.

Refer now to FIGS. 5 and 6, which show a front exploded view and a side view respectively of a blank or form for a magnetic coil assembly 9, in accordance with the invention. An overall or completed coil assembly 9 is shown in FIG. 8. The assembly 9 of FIG. 8 is positionable on the picture tube as indicated in FIGS. 2 and 3 to form a part of the picture tube convergence unit.

The assembly blank or form 10 comprises two essentially identical mating halves or units 11 and 12 which are joined together as will be described hereinbelow. Since the two units 11 and 12 are essentially identical, only a detailed description of unit 11 will be given. The unit 11 comprises a hollow post 14 (see also FIG. 6) having a pair of flanges 15 and 17 on the opposite ends of the post and around the periphery of the post. In the embodiment shown, the post 14 is square in cross section; however, the post '14 may be of any other suitable cross-sectional shape to receive a magnetic (usually ferrite) core therein, as will be explained. I

A U-shaped flange member 21 is mounted intermediate 2 the ends of the posts 14, and comprises a pair of upstanding legs 22 and 23 which surround the posts; the post 14 in efliect passes through each of the legs 22 and 23 of The bight or closed portion 24 of the U- shaped member 21 is spaced from the post 14. Three electrical terminal pins or lugs, generally labelled 25, formed'by pins or lugs are aflixed as by stapling to the bight position 24. mounted by upstanding arms 28 on the upper side (as oriented in FIGS. 5 and 6) of the post 14 (the mating or other half 26b of the guideway comprises part of unit 12). The guideway 26 receives a holder 27 indicated by the dotted lines in FIG. 6 which holds or supports a permanent magnet 29 at its front or righthand end as shown in FIG. 6. As mentioned hereinabove, the per- One half 26a of a guideway 26 is manent magnet 29 effects static convergence of the associated electron beam.

In the manufacturing of the final magnetic assembly of the invention, each half of units 11 and 12 is mounted on a spindle for winding a pair of coils 31 and 33 (see FIG. 8) are Wound thereon. The coils 31 and 33 are in spaced relation to one another; coil 31 is wound on post 14 in the section between flange 15 and leg 22 of flange 21, and coil 33 is wound on post 14 in the section between leg 23 of flange 21 and flange 17. To initiate winding, and for example, one end 31a of the wire which is to form coil 31 is affixed to terminal 25a (see FIG. 8), and then the unit 11 is rotated until enough turns are wound to form coil 31, then the other end 31b of the wire is severed and affixed to terminal 2512. Likewise, to wind coil 33 the one end of 33a of the associated wire is affixed to terminal 250 and unit 11 is rotated until enough turns are wound to form coil 33. Note, however, that the other end 33b of the wire forming coil 33 is left free or unconnected until the two half units 11 and 12 are joined, and the free end 3312 of the wire is connected to a terminal 35d formed on the unit 12. Thus, the flanges 15, 22 and 17 and 23 effectively form spools on which the respective coils 31 and 33 are wound, and the terminal 25 provides convenient means for aifixing the ends of the coils to the units 11 and 12. A

After the coils are wound on the two units 11 and 12, the legs 37 and 38 of a U-shaped core 34, are then inserted through the hollow posts 14 and 114, see FIGS. 1 and 7. The bight 41 of the core and the core legs 37 and 38 hold the units 11 and 12 together, and the posts 14 and 114 are affixed to the core legs 37 and 38 as by glue.

Note that the guideway halves 26a and 2612 are arranged to mate with one another to define a passageway or guideway 26. A spring clip 32, of any suit-abl type, is inserted around guideway halves 26a and 26b to further fasten the two units 11 and 12 together.

Next, the permanent magnet holderi27 is positioned in guideway 26. Note that the guideway 26 is formed to receive the holder 27 at an angle with respect to the plane of the electromagnetic core 34. The permanent magnet 22 carried in the end of the holder 27 is thus adjustable or movable to be positioned closely adjacent the ends of the electromagnetic core 34 as shown in FIG. 7 to thus provide closer spatial relation between the static and the dynamic convergence control. It should be understood that in an actual embodiment the coils 31, 33, etc. would be wound on the respective posts, before the holder 27 (as indicated in FIG. 7) is positioned in' the guideway 26.

While the invention has been particularly shown and described with reference to a preferred embodiment there of, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the inventron.

I claim:

1. A magnetic assembly comprising, in combination, a pair of similar mating units, each unit'incl-uding a hollow post for receiving a respective leg of a magnetic core, flanges formed at spaced points on said posts for defining spools on which coils are wound, an extension connecting selected ones of said fianges, a plurality of terminal pins mounted on said extension for receiving the 'ends of the wires ofsaid coils, each unit having a guideway extending outwardly from said post, said guideway having an essentially C-shaped cross section and having the open ends of said C-shaped guideway mateable with the open ends of the C-shaped guideway of the other unit for positioning and adjustably guiding a holder for a magnet to position said magnet in juxtaposition with the ends of said core, and means for fastening said mating units to one another. a

2. A magnetic convergence assembly for a color television picture tube comprising, in combination, a pair of similar units, each unit including a hollow post for receiving a respective leg of a U-shaped core, a flange formed at either end of said post, a U-shaped flange formed on said post intermediate the ends of said post, a respective end flange and the adjacent leg of the U- shaped flange defining spools on said post on which coils are wound, a plurality of terminals mounted on the bight portion of said U-shaped flange to which the ends of the wires of said coils are connected, and a guideway means extending outwardly from said post and having an essentially C-shaped cross section formed on each unit, said guideway means having its longitudinal axis extending in an angled direction with respect to the longitudinal axis of said hollow post, said guideway means having the open ends of its C-shaped guideway mateable with the open ends of the C-shaped guideway means of the other similar unit for thereby positioning and adjustably guiding a holder for a magnet therein, and means for fastening said units to one another.

3. A magnetic assembly as in claim 1 including a spring clip means positionable about said guideways for holding said guideways in position.

direction forming an angle with the plane of said core legs for positioning said magnet in juxtaposition with the free ends of the legs of said core.

5. A magnetic core assembly as in claim 4 wherein the legs of said core are substantially rectangular in vcross section, said post being shaped to receive said core, and said post being retained in position by said core.

6. A magnetic assembly as in claim 4 wherein two spools or bobbins are formed on each post for receiving respective coils.

7. A magnetic assembly as in claim 2 wherein the wire ends of at least one coil formed on one unit are connected to the terminal pins of an associated unit.

8. A magnetic assembly as in claim 2 where the bight portion of the U-shaped flange is spaced from said post.

References Cited by the Examiner UNITED STATES PATENTS 2,355,477 8/1944 Stahl. 2,897,390 7/1959 Jensen 313-77 FOREIGN PATENTS 131,918 6/ 1929 Switzerland.

4. A magnetic convergence assembly as in claim 2 25 BERNARD GILHEANY Exammer' wherein said guideway means guides said holder in a H. LEWITTER, Assistant Examiner. 

1. A MAGNETIC ASSEMBLY COMPRISING, IN COMBINATION, A PAIR OF SIMILAR MATING UNITS, EACH UNIT INCLUDING A HOLLOW POST FOR RECEIVING A RESPECTIVE LEG OF A MAGNETIC CORE, FLANGES FORMED AT SPACED POINTS ON SAID POSTS FOR DEFINING SPOOLS ON WHICH COILS ARE WOUND, AN EXTENSION CONNECTING SELECTED ONES OF SAID FLANGES, A PLURALITY OF TERMINAL PINS MOUNTED ON SAID EXTENSION FOR RECEIVING THE ENDS OF THE WIRES OF SAID COILS, EACH UNIT HAVING A GUIDEWAY EXTENDING OUTWARDLY FROM SAID POST, SAID GUIDEWAY HAVING AN ESSENTIALLY C-SHAPED CROSS SECTION AND HAVING THE OPEN ENDS OF SAID C-SHAPED GUIDEWAY MATEABLE WITH THE OPEN ENDS OF THE C-SHAPED GUIDEWAY OF THE OTHER UNIT FOR POSITIONING AND ADJUSTABLY GUIDING A 